LM393 Comparator Circuit for ±10V Sensor Monitoring Both Polarities Without Damage

Hello,

I was instructed to design a comparator circuit that needed to compare both polarities. Basically, we have this sensor that goes from +10V to -10V. It cycles because the sensor is attached to a motor. So I need to monitor that output from the sensor constantly for 40 days and if the voltage goes above or below the threshold, the comparator output would go high. I designed the comparator circuit on MultiSim and everything was working very well. Setting up the circuit on the bench didn't give great results. Because of the opposite polarities, power supplies were shorting out and burning up the IC's. After adding multiple resistors and diodes I was able to have the circuit work for a short time. But eventually the opposite polarities were too much for the LM393 to handle and the current was leaking from within the comparator. I am attaching the circuit, could someone help me out with my design? Maybe someone knows exactly how the design should be.

Thanks!

Comparator Circuit Both Polarities

Looks like a standard window comparator, there are numerous circuits on the web.
http://electronics.stackexchange.com/question...9/window-comparator-using-lm339-invert-output.
This link shows a window comparator, and a solution if you need to invert the output. For your application, the ground in the diagram would go to a negative reference instead. Of course, you also need to change the resistor values on the input to give the desired plus and minus ten volts on the respective comparator inputs.
You will need a stable dual supply as a reference. The output is open collector, so can run off a lower supply voltage, i.e logic supply if needs be.
A dual regulated 12V supply as a supply and reference should be fine(Vin comparator max = Vcc-1.5V) This is the sort of thing that Spice won't tell you. The lm339 is a 36 volt max supply device.
You will possibly have a very noisy input, so you will need some sort of noise filtering I would think,
cheers,
Richard

Thanks Richard,

I don't need to invert the output though. When I try wiring up the circuit per my schematic, the -9.25V and the +9.25V want to short out within the comparator. I added multiple resistors to lower the current so they wouldn't short but then I don't get enough voltage behind it to even compare the two negative signals. In my schematic, the VCC (0V) on the left will be going up to +10V and back down to -10V. The comparator works great for the +10V but as soon as VCC goes to negative voltage, the comparator burns up because the polarities are shorting out somewhere.